[argyllcms] Re: conjgrad failed
- From: Mickael Profeta <profeta@xxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 13 Aug 2006 18:44:33 +0200
Hi
>
> This is a rather unusual value for black. You performed a calibration,
> so are you sure you performed it correctly ? At the first step of
> the calibration, did you place the instrument on completely black
> surface,
> and in a dark place (ie. something opaque over the instrument), or did
> you accidentally have it on the screen at the time ?
> Doing the latter will cause the screen black to read 0.0, or even
> -ve, possibly causing the numerical errors that follow.
>
You are right, the problem is certainly that one.
Yet it seems it loses this step.
If I add the -a flag, it asks to place the instrument on a black surface
(which was not asked before), the first measurement looks fine, but when
it really starts the calibration in itself, the black value seems odd,
not taking into account the forst step?
here is a tipical output:
alezan:/home/mike/argyll3/argyll-0.60/spectro# ./dispcal -i92 -a -v
/tmp/targen
Setting up the instrument
Offset calibration:
Place instrument on a dark surface.
Hit Esc to skip, any other key to start calibration:
Offset calibration successful
The instrument can be removed from the dark surface.
Cell ratio calibration:
Place instrument on test window.
Hit Esc to skip, any other key to start calibration:
Cell ratio calibration successful
The instrument can be removed from the screen.
Setting up the instrument
Place instrument on test window.
Hit Esc to give up, any other key to continue:
Target white = native white
Target brightness = native brightness
Target gamma = 2.200000
Press 1 .. 7
1) Black level (CRT: Brightness)
2) White point (Color temperature, R,G,B, Gain)
3) White level (CRT: Contrast, LCD: Brightness)
4) Black point (R,G,B, Offset)
5) Check all
6) Continue on to calibration
7) Exit
Doing check measurements
Current Brightness = 70.57
Target 50% Level = 15.36, Current = 13.99, error = -1.9%
Target Near Black = 0.71, Current = 0.99, error = 0.4%
Current white = x 0.3224, y 0.3284, VDT 6251K DE 6.7
Target black = x 0.3224, y 0.3284, Current = x 0.5879, y 0.3333, error
= 33.35 DE
Press 1 .. 7
1) Black level (CRT: Brightness)
2) White point (Color temperature, R,G,B, Gain)
3) White level (CRT: Contrast, LCD: Brightness)
4) Black point (R,G,B, Offset)
5) Check all
6) Continue on to calibration
7) Exit
Commencing device calibration
patch 6 of 6
Black = XYZ 999.99 0.00 999.99
Red = XYZ 31.09 14.61 0.22
Green = XYZ 24.39 47.13 6.82
Blue = XYZ 12.22 3.31 59.62
White = XYZ 69.46 70.51 75.29
patch 64 of 64
Initial native brightness target = 70.510000 cd/m^2
Had to scale brightness from 70.510000 to 70.362598 to fit within gamut
Target white value is XYZ 69.314793 70.362598 75.132606
Target black point = nan 0.000000 nan
Gamma curve offset = 0.000000
Creating initial calibration curves...
dispcal: Error - Conjgrad failed
Thanks
Mike
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